Re: DNA and ffingerprints
Exactly. I spent a good many years as a forensic scientist. Although it wasn't a frequent occurrence we did see a few occasions where the defence called an expert. We had doubts as to the actual level of expertise, especially given the fact that they would claim expertise over much wider areas of the laboratory's work than individual staff members would, and given that we would sometimes have to show them how to operate a particular make of microscope. There were also a few, possibly apocryphal, tales of these independent experts arguing a case from a standpoint of ignorance; an industrial QA operator not aware of how to measure, say the RI of glass to a couple of orders of magnitude better than all that QA required.